E. J. Spratling
The following quote alludes the mechanical changes in the penis upon removal of the foreskin: the mobility of the skin is limited, destroying the gliding effect of the foreskin.
"In all cases of masturbation circumcision is undoubtedly the physician's closest friend and ally... To obtain the best results one must cut away enough skin and mucous membrane to rather put it on the stretch when erections come later. There must be no play in the skin after the wound has thoroughly healed, but it must fit tightly over the penis, for should there be any play the patient will be found to readily resume his practice, not begrudging the time and extra energy required to produce the orgasm. It is true, however, that the longer it takes to have an orgasm, the less frequently it will be attempted, consequently the greater the benefit gained... The younger the patient operated upon the more pronounced the benefit, though occasionally we find patients who were circumcised before puberty that require a resection of the skin, as it has grown loose and pliant after that epoch." E.J.Spratling, Masturbation in the Adult, Medical Record, vol. 24. (1895): pp. 442-443.